102 Wssconsin Academy of Sciennes, Arts, and Letters. 



SPECIES I. 

 Plate I. Fig. 18. 



Crepidocercus Setiger. sp. nov. 



Length, 0.4-0.5 mm. Height, 0.27-0.32 mm. 

 Measurements from one specimen. 



Length, 0.87 mm. Height, 0.25 mm. Length of hind margin, 

 0.12 mm. Length of spine of ventral margin, 0.017 mm. Length 

 of setse of ventral margin, 0.02-0.04 mm. Diameter of eye, 

 0.028 mm. Diameter of macula nigra, 0.01. Length of anten- 

 nule, O.Ol-l mm. Length of post-abdomen from " heel " to "toe," 

 0.11 mm. Length of terminal claw, 0.016 mm. This specimen 

 was rather below the average in size. 



The color is yellow, rather opaque. The specific name is taken 

 from the setae with which the post-abdomen is armed. Mad- 

 ison, Wis. Eare. Male not seen. 



This species is to some degree intermediate between Alona and 

 Pleuroxus. It resembles the first in the size of the rostrum and 

 the single basal spine of the terminal claws. In general shape 

 and markings it recalls Pleuroxus. Grraptoleberis is the only 

 form whose post-abdomen at all resembles that of Crepidocercus. 

 The mode of motion is quite peculiar. 



GENUS 4. 

 G-raptoleberis. Sars, 1867. 



Gkaptolebekis. Kurz. 



Alona, e. p. Baird, Schodler, P. E. Muller. 



Ltnceus, e. p. Leydig, Liljeborg, Fischer et al. 



SPECIES 1. 

 Plate I. Fig. 17. 



G-RAPTOLEBERIS InERMIS. sp. noV. 

 Length, 0.6-0.8 mm. Height, 0.30-0.35 mm. 



There is no indentation at the junction of head and thorax, but 

 the dorsal margin rounds regularly over from the point of the 



